MRG LPF/a (Bare PCB) Assembly Guide

This is the assembly guide for the MRG LPF/a bare PCB build. If you have a SMD presoldered PCB, check the MRG LPF/a presoldered assembly guide.

This build should be considered of medium difficulty given the number of components and steps required.

Theory of operation:

  1. If you bought the PCB+Panel+IC only, acquire needed components (See Bill of Materials. All components used in this guide are already included in the full DIY kit.
  2. Build the Main PCB.
  3. Build the Front PCB.
  4. Module assembly.

Main PCB build

Step A1. Start by soldering all horizontal resistors and the diode.

lpf pcb

Step A2. Solder all ceramic capacitors.

lpf pcb

Step A3. Solder the AS3320 IC and the 2x5 pin header. If desired, a 18-pin socket can be soldered on the PCB, instead of directly soldering the IC.

lpf pcb

Step A4. Solder the TL072 ICs. If desired, 8-pin sockets can be soldered on the PCB, instead of directly soldering the ICs.

lpf pcb

Step A5. Solder the four PP Capacitors.

lpf pcb

Step A6. Solder the electrolytic capacitors.

lpf pcb

Everything apart from the two 14-pin headers are soldered on the board now. It is time to solder the front PCB.

Front PCB

Step B1 Check the alignment of the PCB (label U1 is the top row), arrange the jack sockets and the potentiometers.

lpf pcb

Step B2. Solder the components. Tip: in order to be sure to align the components to the front panel, install the front panel as in photo below and solder the components on the back.

lpf pcb

Step B3. Solder the socket headers. Tip: In order to align the Main PCB's pin headers to the Front PCB's socket headers, assemble the two PCBs together, as in picture, and solder them in place.

lpf pcb

All soldering is now done! The next step is installing the front panel.

Final Module Assembly

Install the front panel, using nuts and washers to keep it attached, and add the knobs to the potentiometers.

Congratulations! You have concluded a fairly complex build!

Feedback? Suggestions? Contact me!.

Bill of Materials

This is the required bill of materials if you bought the PCBs+Panel+IC only. All components listed below are already included in the full DIY kit.

Resistors usually included in the kit are usually Multicomp MF12 Series.

Note: Use of 1% tolerance 3.5mm resistors highly recommended.

Component Quantity




1K11marked 1100 on PCB

Ceramic Capacitors:

100nF (104) 6
1uF (105) 1

Other Capacitors:

22uF Electrolitic Capacitor 2 Rubycon 25ZLG22MEFC5X7
220pF Film Capacitor 3 5mm pitch PP film reccommended
100pF Film Capacitor 1 5mm pitch PP film reccommended

Other Components:

1N4148 Diode 1 DO-35
14 Pin 2 Row Header2
14 Pin 2 Row Socket2
10 Pin 2 Row Header1
B100K4Alpha 9mm T18 Potentiometer
PJ398SM 3.5mm Jacks4